<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <link rel="stylesheet" href="./css/index.css" />
    <title>记事本</title>
  </head>
  <body>
    <!-- 主体区域 -->
    <section id="app">
      <!-- 输入框 -->
      <header class="header">
        <h1>小黑记事本</h1>
        <!-- 给 表单元素 使用, 双向数据绑定 快速 获取 或 设置 表单元素内容 -->
         <!-- $event 事件对象 -->
        <!-- <input @keyup="submit($event)" placeholder="请输入任务" class="new-todo" v-model="testvalue" /> -->
        <input @keyup.enter="submit" placeholder="请输入任务" class="new-todo" v-model="testvalue" />
        <button class="add" @click="add()">添加任务</button>
      </header>
      <!-- 列表区域 -->
      <section class="main">
        <ul class="todo-list">
          <li class="todo" v-for="(item, index) in booksList" :key="item.id">
            <div class="view">
              <span class="index">{{index + 1}}</span>
              <label>{{item.name}}</label>
              <button class="destroy" @click="del(item.id)"></button>
            </div>
          </li>
        </ul>
      </section>
      <!-- 统计和清空 -->
      <footer class="footer" v-show="booksList.length > 0">
        <!-- 统计 -->
        <span class="todo-count"
          >合 计:<strong>{{booksList.length}}</strong></span
        >
        <!-- 清空 -->
        <button class="clear-completed" @click="reset()">清空任务</button>
      </footer>
    </section>

    <!-- 底部 -->
    <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
    <script>
      const app = new Vue({
        el: "#app",
        data: {
          booksList: [
            { id: 1, name: "吃饭" },
            { id: 2, name: "睡觉" },
          ],
        },
        methods: {
          // 添加
          add() {
            if (!this.testvalue) {
              return alert("请输入内容");
            }
            this.booksList.unshift({
              id: this.booksList.length + 1,
              name: this.testvalue,
            });
            // 内容添加后，输入框清空
            this.testvalue = "";
          },
          // 删除
          del(id) {
            // 保留所有不等于该 id 的项
            this.booksList = this.booksList.filter((item) => item.id !== id);
          },
          // 清空任务
          reset() {
            this.booksList = [];
          },
          submit(e){
            // if (e.key === "Enter") {
              this.add()
            // }
          },
        },
      });
    </script>
  </body>
</html>
